Default to root-path-redirection on the base domain if index.html creation is disabled

This is a break in backward-compatibility for people disabling
`index.html` creation via the playbook but are managing their static
website files in another way (AUX role, etc).

group_vars/matrix_servers

@@ -4848,6 +4848,10 @@ matrix_static_files_container_labels_well_known_matrix_endpoint_traefik_hostname
 # but we pass the hostname, so that enabling it is easy.
 matrix_static_files_container_labels_base_domain_traefik_hostname: "{{ matrix_domain }}"
 
+# If we're not serving a static webpage, serve a redirect instead of a 404.
+matrix_static_files_container_labels_base_domain_root_path_redirection_enabled: "{{ not matrix_static_files_file_index_html_enabled }}"
+matrix_static_files_container_labels_base_domain_root_path_redirection_url: "https://{{ matrix_server_fqn_matrix }}"
+
 matrix_static_files_file_matrix_client_property_io_element_jitsi_preferred_domain: "{{ matrix_server_fqn_jitsi if jitsi_enabled else '' }}"
 
 matrix_static_files_file_matrix_client_property_org_matrix_msc3575_proxy_url: "{{ matrix_homeserver_sliding_sync_url }}"

roles/custom/matrix-static-files/defaults/main.yml

@@ -81,6 +81,9 @@ matrix_static_files_container_labels_base_domain_traefik_priority: 0
 matrix_static_files_container_labels_base_domain_traefik_entrypoints: "{{ matrix_static_files_container_labels_traefik_entrypoints }}"
 matrix_static_files_container_labels_base_domain_traefik_tls: "{{ matrix_static_files_container_labels_base_domain_traefik_entrypoints != 'web' }}"
 matrix_static_files_container_labels_base_domain_traefik_tls_certResolver: "{{ matrix_static_files_container_labels_traefik_tls_certResolver }}"  # noqa var-naming
+# Controls whether the root path (/) at the base domain would respond with a redirect to some URL.
+matrix_static_files_container_labels_base_domain_root_path_redirection_enabled: false
+matrix_static_files_container_labels_base_domain_root_path_redirection_url: ""
 
 # matrix_static_files_container_labels_additional_labels contains a multiline string with additional labels to add to the container label file.
 # See `../templates/labels.j2` for details.
@@ -343,6 +346,9 @@ matrix_static_files_file_matrix_support_configuration: "{{ matrix_static_files_f
 #
 # You can also use the auxiliary role (https://github.com/mother-of-all-self-hosting/ansible-role-aux) to create files in
 # the public directory (matrix_static_files_public_path) by yourself.
+# If you're disabling this but are preparing some HTML files by yourself,
+# consider explicitly disabling `matrix_static_files_container_labels_base_domain_root_path_redirection_enabled` as well.
+# The default behavior when this is disabled is to enable root-path-redirection.
 #
 # Because you may wish to manage these static files yourself, disabling this variable will intentionally not delete an already existing `index.html` file.
 matrix_static_files_file_index_html_enabled: "{{ matrix_static_files_container_labels_base_domain_enabled }}"

roles/custom/matrix-static-files/tasks/validate_config.yml

@@ -11,3 +11,5 @@
 
     - {'name': 'matrix_static_files_container_labels_base_domain_traefik_hostname', when: "{{ matrix_static_files_container_labels_base_domain_enabled }}"}
     - {'name': 'matrix_static_files_container_labels_base_domain_traefik_path_prefix', when: "{{ matrix_static_files_container_labels_base_domain_enabled }}"}
+
+    - {'name': 'matrix_static_files_container_labels_base_domain_root_path_redirection_url', when: "{{ matrix_static_files_container_labels_base_domain_enabled and matrix_static_files_container_labels_base_domain_root_path_redirection_enabled }}"}

roles/custom/matrix-static-files/templates/labels.j2

@@ -56,12 +56,24 @@ traefik.http.routers.{{ matrix_static_files_identifier }}-well-known.tls.certRes
 #                                                          #
 ############################################################
 
+{% set middlewares = [] %}
+
+{% if matrix_static_files_container_labels_base_domain_root_path_redirection_enabled %}
+traefik.http.middlewares.{{ matrix_static_files_identifier }}-root-path-redirect.redirectregex.regex=^https://{{ matrix_static_files_container_labels_base_domain_traefik_hostname }}{{ matrix_static_files_container_labels_base_domain_traefik_path_prefix }}$
+traefik.http.middlewares.{{ matrix_static_files_identifier }}-root-path-redirect.redirectregex.replacement={{ matrix_static_files_container_labels_base_domain_root_path_redirection_url }}
+{% set middlewares = middlewares + [matrix_static_files_identifier + '-root-path-redirect'] %}
+{% endif %}
+
 traefik.http.routers.{{ matrix_static_files_identifier }}-base-domain.rule={{ matrix_static_files_container_labels_base_domain_traefik_rule }}
 
 {% if matrix_static_files_container_labels_base_domain_traefik_priority | int > 0 %}
 traefik.http.routers.{{ matrix_static_files_identifier }}-base-domain.priority={{ matrix_static_files_container_labels_base_domain_traefik_priority }}
 {% endif %}
 
+{% if middlewares | length > 0 %}
+traefik.http.routers.{{ matrix_static_files_identifier }}-base-domain.middlewares={{ middlewares | join(',') }}
+{% endif %}
+
 traefik.http.routers.{{ matrix_static_files_identifier }}-base-domain.service={{ matrix_static_files_identifier }}
 traefik.http.routers.{{ matrix_static_files_identifier }}-base-domain.entrypoints={{ matrix_static_files_container_labels_base_domain_traefik_entrypoints }}
 traefik.http.routers.{{ matrix_static_files_identifier }}-base-domain.tls={{ matrix_static_files_container_labels_base_domain_traefik_tls | to_json }}